@Graysky : Thanks. I faced the same problem, and the solution you suggested worked for me as well.
--Gphilip 02:48, 29 August 2011 (EDT)

I had the same problem, but I found another solution: computerA has a working arch linux install, computerB has the empty partition. Use sshfs to mount computerB:/newarch to computerA:/newarch, and run pacman from computerA (with -r of course).
--jpic 09:53 UTC, 04 April 2012 (EDT)